NICE, France (AP) -- Top-seeded Gilles Simon of France withdrew from the Open de Nice on Wednesday, casting doubts on his French Open participation.
Simon, who retired from his second-round match in Madrid this month, says "I'm extremely sorry to withdraw from the Nice Open. The pain is too strong."
The French Open starts on Sunday.
The 13th-ranked Simon was set to face James Duckworth of Australia for a quarterfinal spot and will be replaced by French lucky loser Quentin Halys.
Fourth-seeded Leonardo Mayer advanced to the last-eight with a 6-4, 6-0 win over French wild-card entry Lucas Pouille to set up a meeting against Juan Monaco.
Dominic Thiem also progressed when sixth-seeded Nick Kyrgios retired while trailing 4-3 in the first set.